Take the reigning queen of bombshell cool, Kate Moss. Snapped walking her Staffordshire mix, Archie, in London yesterday, her artfully rumpled layers suggested the kind of girl who indulges in the occasional on-duty blowout, only to let blasts of dry shampoo and the English breeze restyle it to a brilliantly lived-in texture. It’s an impulse worth keeping in mind over the holidays, when the call for festive polish meets the urge to be as lazy as possible: Take an extra few minutes to blow-dry your hair just right and it’s the gift that keeps on giving.